The allelopathic activity of striga asiatica extract on chlorella vulgaris (UMT-M1)

Abstract

Allelopathy is a common occurrence in plants and affects the growth of the reacting species either positive (stimulating) or negative (inhibiting). Allelopathic activity has been in many plant interactions such as weed on crops, crops on weeds and crops on crops. Weed allelopathy is important for the future agronomic applications especially in crops production. Striga asiatica has been known as the invasive weed species that inhibit the growth of important crops. The present study examined the allelopathic activity of Striga asiatica on microalgae Chiarella vulgaris (UMT-Ml) . Crude and supernatant extract of S. asiatica at two, four and six weeks of culture were tested using the algal plating assay with disc diffusion and agar well diffusion method. Results showed that crude extract of S. asiatica with agar well method causes positive allelopathic activity on the growth of Chlorella vulgaris (UMT-Ml) with formation of dense green zone around the agar well. The highest extract concentration, 50 mg/ml exhibited the highest stimulating allelopathic activity on the growth of Chlorella vulgaris (UMT-Ml) by showing the widest stimulating zone radius. The four weeks old of S. asitaca culture also contributed highest allelopathic activity with significance level at P<0.05. Allelopathic activity is dependent on the age of plantlets and concentration used on the microalgae.